Discordant hepatitis C serological testing in Australia and the implications for organ transplant programs.

BACKGROUND: Discordant and equivocal hepatitis C (HCV) serology testing is problematic for making decisions regarding deceased organ donor (DOD) transplant allocation based on allograft infection status. OBJECTIVES: This study aimed to analyse the prevalence and follow-up testing of discordant HCV tested patients from an Australian population at increased risk of HCV infection, with prevalence modelling for the Australian DOD population. STUDY DESIGN: De-identified patient discordant HCV serology results (primary chemiluminescent microparticle immunoassay and secondary Bio-Rad MonoLisa HCV Ag/Ab Ultra assay) were retrospectively identified in a general referral laboratory between May 2008 and August 2011. Prior and follow-up serology testing was reviewed. Discordant result prevalencewas calculated using Bayes' theorem for the DOD population using Australian DOD rates and HCV seroprevalence. RESULTS: The tested population had a 6.6% HCV seroprevalence. The rate of discordant serotesting was 0.54%, with no cases identified as having definite HCV infection at follow-up. Two patients had evidence of definite HCV seropositivity before the index discordant test. Modelling for the Australian DOD population of 337 per year estimated a discordant test prevalence of 1.8 per year. CONCLUSIONS: Discordant HCV serotesting may occur for 1 of 185 patients tested in higher risk populations. The majority of such tests represent falsely reactive tests although a small number may reflect partial seroreversion. Amongst Australian DOD, this represents 1 or 2 discordant cases per year. It is likely that if this discordant sample were from a donor with no blood borne virus risk factors, and was concurrently RNA negative, that HCV infectious risk would be extremely low.

Clinical aspects of cytomegalovirus antiviral resistance in solid organ transplant recipients.

Despite advances in the prophylaxis and acute treatment of cytomegalovirus (CMV), it remains an important pathogen affecting the short- and long-term clinical outcome of solid organ transplant. The emergence of CMV resistance in a patient reduces the clinical efficacy of antiviral therapy, complicates therapeutic and clinical management decisions, and in some cases results in loss of the allograft and/or death of the patient. There is increasing use of antiviral prophylaxis after transplant with little expansion in the range of antiviral agents effective in treatment of CMV. Further understanding is needed of the risk factors for development of CMV antiviral resistance and of therapeutic strategies for treating patients infected with resistant viruses. We review the current status of CMV resistance in solid organ transplant recipients, and provide diagnostic and therapeutic suggestions for the clinician in managing antiviral resistance.